Atraumatic micropuncture guidewire and guidewire extension

ABSTRACT

A guidewire introducable into a bodily lumen having an obstruction therein is provided. An introducer needle is advanced through tissue and into the bodily lumen. A guidewire is advanced through the introducer and into the lumen. The guidewire is advanced further through the lumen until an atraumatic distal tip of the guidewire encounters an obstruction the distal tip cannot pass in a straight forward manner. The distal tip is pressed against the obstruction such that a flexible segment proximal of the distal tip forms a loop distal of the distal tip. The guidewire is advanced further through the lumen such that the loop of the flexible segment is pushed past the obstruction and the distal tip is pulled distally past the obstruction. A greater diameter guidewire extension can be coupled to the back end of the guidewire, providing function as a larger diameter guidewire.

CROSS-REFERENCE

This application claims the benefit of the following provisional patentapplications: Ser. Nos. 62/192,392, filed Jul. 14, 2015, 62/137,583,filed Mar. 24, 2015, 62/136,733, filed Mar. 23, 2015 and 62/121,589,filed Feb. 27, 2015, the contents of which are fully incorporated hereinby reference.

BACKGROUND

The present disclosure relates to medical devices, systems, and methods.In particular, the present disclosure relates to guidewires used inmicropuncture sets and many medical procedures.

Many minimally invasive medical procedures rely on catheters and othersimilar devices introduced and advanced through the vasculature or otherbodily lumens. In many cases, such devices are advanced over a guidewirethat has been navigated through the vasculature or bodily lumen. Often,the guidewire itself has been introduced first through an introducerneedle puncturing tissue and accessing the vasculature or other bodilylumen and then through the vasculature or bodily lumen. The guidewiremay then be advanced and navigated toward a target region.

In some medical procedures, small diameter or micropuncture guidewiresmay be used. For example, regular guidewires may have a diameter ofabout 0.035″ while micropuncture guidewires may have a diameter of0.018″. Current micropuncture guidewires may be less than ideal in atleast some cases. For example, many micropuncture guidewires mayencounter a high degree of friction as they are advanced through thelumen of a small gauge introducer needle. Due to the friction, theoperator of the guidewire may lose much tactile feedback. It maytherefore be difficult for the operator to discern resistance from theguidewire versus resistance from the micropuncture guidewireencountering plaque or other obstructions in the vasculature or bodilylumen. In some cases, the operator may mistake resistance from plaque orthe guidewire abutting the wall of the vessel as resistance from theneedle, apply excessive forward force to the guidewire, andinadvertently puncture or dissect the wall of a blood vessel with theguidewire tip. Micropuncture guidewires also may have a smaller diameterthan standard guidewires. Therefore, the force exerted by the tip ofmicropuncture guidewires can be concentrated on a smaller area, whichmay increase the likelihood of perforating, puncturing, or otherwisecausing trauma to tissue. An additional risk of using currentlyavailable micropuncture sets may be that after removing themicropuncture needle, in order to enlarge the entry hole into the vesselor body lumen, two coaxial dilators, an inner one with a 0.018″ innerdiameter and an outer one with a 0.035″ inner diameter, are typicallyintroduced over the micropuncture guidewire. The inner dilator may thenbe removed together with the 0.018″ guidewire thus leaving in place a0.035″ inner diameter dilator. The remaining outer dilator can allow theintroduction of a larger 0.035″ guidewire, which must successfullyre-cross the segment of the vessel or body cavity which had beenpreviously crossed with the initially introduced 0.018″ guidewire. Theattempted re-crossing may pose an additional injury threat and it may bedifficult or even impossible to successfully re-cross the vessel or bodycavity. There are therefore needs for improved micropuncture guidewiresto overcome such disadvantages.

References that may be of interest may include U.S. Pat. Nos. 7,824,345,7,169,118, 5,507,729, 5,368,049, 5,282,478, 5,133,364, 5,060,660,4,991,602, and 4,796,642 and U.S. Pub. Nos. 2011/0071435 and2009/0187147. Many of these references show guidewires and extensionswith the same diameter and describe nothing specifying or implying theneed for or rationale for different diameter guidewires and extensions.Some of these references also specify that guidewires and theirextensions be of the same diameter.

SUMMARY

Aspects of the present disclosure provide a guidewire apparatusadvanceable through a bodily lumen or vessel. The guidewire apparatusmay comprise a rounded distal tip, a flexible neck segment, and anelongate segment. The rounded distal tip may have a first diameter. Theflexible, neck segment may be proximal of the rounded distal tip and mayhave a second diameter less than the first diameter. The flexible necksegment may be straight, curved, or shapeable. The elongate segment maybe proximal of the neck segment and may have a third, fourth, or furtherdiameter(s) greater than the second and/or subsequent diameter(s). Whenthe guidewire apparatus encounters an obstruction as it is advancedthrough the bodily lumen, it may be steered, directed, and advanced pastthe obstruction as other similar conventional guidewires can be made todo. However, when the guidewire apparatus is unable to be advanced pastthe obstruction as described, the flexible neck segment may beconfigured to assume a loop form as the rounded distal tip encountersthe obstruction. The loop may be disposed distally of the rounded distaltip when formed. Further advancement of the guidewire may push the looppast the obstruction so that the rounded distal tip is ultimately pulledpast the obstruction.

One or more of the rounded distal tip, the flexible neck segment, or theelongate segment may be covered with a coating. The coating may compriseone or more of a radiopaque coating, a hydrophobic coating, ahydrophillic coating, an anti-thrombogenic coating, a polymeric coating,a silicone coating, or a polytetrafluoroethylene (PTFE) coating, to namea few.

The guidewire apparatus may comprise a single piece extrusion or grindwithout joints or welds. The guidewire apparatus may be made of amaterial comprising one or more of platinum, gold, silver, NiTi, steel,steel alloy, stainless steel, stainless steel alloy, titanium, titaniumalloy, aluminum, aluminum alloy, tungsten, or tungsten alloy, to name afew.

The guidewire apparatus may comprise a micropuncture guidewire. Thefirst diameter, or the diameter of the rounded distal tip, may be about0.018 inches and the second diameter, or the diameter of the flexibleneck segment, may be about 0.010. In some embodiments, the flexible necksegment may comprise (sub) segments or (sub) sections of severaldiameters which increase proximally with tapered transition(s). Forinstance, the second diameter, or the diameter of a distal section ofthe flexible neck segment may be about 0.002 inches; a third diameter,or a diameter of a middle section of the flexible neck segment, may beabout 0.004 inches; and, a fourth diameter, or a diameter of a proximalsection of the flexible neck segment, may be about 0.010 inches; and,further optionally, a fifth diameter, or a diameter of the elongatesection of the guidewire proximal flexible neck segment, may be about0.018 inches. These dimensions of the guidewire apparatus are disclosedas an example only and other dimensions are contemplated. The guidewireapparatus will typically be scalable and adaptable for other guidewiresizes, such as “standard” non-micropuncture guidewires of any diameterand length. For example, the guidewire apparatus may be adapted for usewith a typical 145 cm or 180 cm long and 0.035 inch diameter guidewire,according to many embodiments.

The bodily lumen the guidewire apparatus may be advanced through maycomprise a bodily duct, a bodily track, a bodily orifice, a bodilyinvagination, a blood vessel, an artery, a vein, a urethra, a ureter, avagina, a fallopian tube, a rectum, a throat, an ear canal, a nasaltract, a bile duct, a biliary tract, an esophagus, a trachea, abronchus, or an artificial bodily tract or lumen, to name a few. In manyembodiments, the bodily lumen comprises a blood vessel and theobstruction comprises plaque therein.

The rounded distal tip may be biased to return to a position distal ofthe flexible segment after the loop of the flexible neck segment isadvanced past the obstruction and the rounded distal tip is pulled pastthe obstruction. The flexible neck segment may be biased so that theloop straightens after the loop of the flexible neck segment is advancedpast the obstruction and the rounded distal tip is pulled past theobstruction.

The elongate segment proximal of the neck segment may comprise a firstportion having the third diameter and a second portion having a fourthdiameter different than the third diameter. The fourth diameter may begreater than the third diameter. The first portion of the elongatesegment may be axially separate from the second portion of the elongatesegment. For example, the greater diameter second portion may beproximal (or closer to the user-operated end) of the lesser diametersecond portion.

The guidewire apparatus may further comprise a wire braid or coildisposed over and supporting the flexible, neck segment. The wire braidor coil may be attached to the flexible, neck segment. The wire braid orcoil may be at least partially disposed over one or more of a distaltapering region between the rounded distal tip and the flexible, necksegment or a proximal tapering region between the elongate segment andthe flexible, neck segment. A combined diameter of the wire braid orcoil and the flexible, neck segment will typically be less than thethird diameter of the elongate segment

Aspects of the present disclosure also provide a guidewire apparatusadvanceable through a bodily lumen. The guidewire apparatus may comprisean atraumatic distal tip, a flexible segment, and an elongate segment.The atraumatic distal tip may have a first stiffness. The flexiblesegment may be proximal of the atraumatic distal tip and may have asecond stiffness less than the first stiffness. The elongate segment maybe proximal of the flexible segment and may have a third stiffnessgreater than the second stiffness. The flexible segment may beconfigured to form into a loop as the guidewire apparatus is advancedthrough the bodily lumen and the atraumatic distal tip encounters anobstruction. The loop may be disposed distally of the atraumatic distaltip when formed. Further advancement of the guidewire may push the looppast the obstruction so that the atraumatic distal tip is pulled pastthe obstruction.

One or more of the atraumatic distal tip, the flexible segment, or theelongate segment is covered with a coating or several coatings. Forexample, the atraumatic distal tip may be coated with a soft coating tominimize trauma caused by contact of the distal tip with tissue.Alternatively or in combination, the atraumatic distal tip may berounded to minimize such potential trauma. The coating may comprise aradiopaque coating, a hydrophobic coating, a hydrophillic coating, ananti-thrombogenic coating, a polymeric coating, a silicone coating, or apolytetrafluoroethylene (PTFE) coating, to name a few.

One or more of the atraumatic distal tip or the elongate segment maycomprise a first material, and the flexible segment may comprise asecond material different from and more flexible than the firstmaterial.

Alternatively, one or more of the atraumatic distal tip or the elongatesegment may comprise a first material, and the flexible segment maycomprise the same first material. The flexible segment may bemechanically modified to be more flexible than one or more of theatraumatic distal tip or the elongate segment. For example, the flexiblesegment may have one or more slots or cuts (e.g., cut into the shape ofa coil spring) to provide flexibility. One or more of the atraumaticdistal tip, flexible segment, or elongate segment may have the samediameter. For example, each of the atraumatic distal tip, flexiblesegment, and elongate segment may have the same diameter. Alternatively,the flexible segment may have a smaller diameter than the atraumaticdistal tip and the elongate segment. In some embodiments, the flexiblesegment may comprise a neck segment having an hourglass-like shape(i.e., a shape having tapers toward the middle on both axial ends).

Exemplary materials the guidewire apparatus may be made of includeplatinum, gold, silver, NiTi, steel, steel alloy, stainless steel,stainless steel alloy, titanium, titanium alloy, aluminum, aluminumalloy, tungsten, and tungsten alloy, to name a few.

The bodily lumen the guidewire apparatus may be advanced through maycomprise a bodily duct, a bodily track, a bodily orifice, a bodilyinvagination, a blood vessel, an artery, a vein, a urethra, a ureter, avagina, a fallopian tube, a rectum, a throat, an ear canal, a nasaltract, a bile duct, a biliary tract, an esophagus, a trachea, abronchus, or an artificial bodily tract or lumen, to name a few. In manyembodiments, the bodily lumen comprises a blood vessel and theobstruction comprises plaque therein.

The atraumatic distal tip may be biased to return to a position distalof the flexible segment after the loop of the flexible segment isadvanced through the obstruction and the atraumatic distal tip is pulledthrough the obstruction. The flexible segment may be biased so that theloop straightens after the loop of the flexible segment is advanced pastthe obstruction and the atraumatic tip is pulled past the obstruction.

The guidewire apparatus may further comprise a wire braid or coildisposed over and supporting the flexible segment. The braid or wirecoil may be attached to the flexible segment. The wire braid or coil maybe at least partially disposed over one or more of a distal transitionregion between the atraumatic distal tip and the flexible segment or aproximal transition region between the elongate segment and the flexiblesegment. A combined diameter of the wire braid or wire and the flexible,neck segment is less than a diameter of the elongate segment.

Aspects of the present disclosure may further provide a method ofintroducing a guidewire into a bodily lumen having an obstructiontherein. An introducer needle may be advanced through tissue and intothe bodily lumen. A guidewire may be advanced through a lumen of theintroducer needle and into the bodily lumen. The guidewire may beadvanced further through the bodily lumen until an atraumatic distal tipof the guidewire encounters an obstruction. The guidewire may beadvanced or steered past these obstructions with its atraumatic tipleading. On occasion, the atraumatic distal tip may not pass and bepressed against the obstruction such that a flexible segment proximal ofthe atraumatic distal tip forms a loop distal of the atraumatic distaltip. The guidewire may be advanced further through the bodily lumen suchthat the loop of the flexible segment is pushed past the obstruction andthe atraumatic distal tip is pulled distally past the obstruction by theloop of the flexible segment.

After the loop of the flexible segment is advanced past the obstructionand the atraumatic distal tip is pulled distally past the obstruction,the atraumatic distal tip may resiliently return to a position distal ofthe flexible segment and the loop of the flexible segment maystraighten.

The bodily lumen the guidewire may be advanced through may comprise abodily duct, a bodily track, a bodily orifice, a bodily invagination, ablood vessel, an artery, a vein, a urethra, a ureter, a vagina, afallopian tube, a rectum, a throat, an ear canal, a nasal tract, a bileduct, a biliary tract, an esophagus, a trachea, a bronchus, or anartificial bodily tract or lumen, to name a few. In many embodiments,the bodily lumen comprises a blood vessel and the obstruction comprisesplaque therein.

To support the flexible segment as it is advanced through the bodilylumen, a wire braid or coil may be coupled to the flexible segment. Thewire braid or coil may be disposed over the flexible segment.

Aspects of the present disclosure also provide extension guidewireapparatuses for coupling to guidewires, such as the guidewire extensionsdescribed above and herein. A guidewire extension apparatus may comprisea far end portion, a near end portion, and a tapering transition portiontherebetween. The far end portion may have a first diameter matching adiameter of a near end of the guidewire. The far end portion may beconfigured to couple with the near end of the guidewire. For example,the far end portion may be configured to couple with the near end of theguidewire with a male-female connection such as a snap-fit, aninterference fit, or a threaded fit. The near end portion may have asecond diameter greater than the first diameter. For example, the firstdiameter and the diameter of the near end of the guidewire may be both0.018″, and second diameter of the near end portion is 0.035″. One ormore of the far end portion, the near end portion, or the taperedportion is covered with a lubricious coating such as any of the coatingdescribed above and herein.

Aspects of the present disclosure also provide methods for introducing amicropuncture guidewire, such as the micropuncture guidewire apparatusdescribed above and herein, and a guidewire extension, such as theguidewire extension apparatus described above and herein, into a bodilylumen, such as any of the bodily lumens described above and herein. Amicropuncture needle may be penetrated through tissue to access thebodily lumen. The micropuncture guidewire may be advanced through themicropuncture needle and into the bodily lumen such that a near orproximal end of the micropuncture guidewire remains outside of thetissue. The micropuncture needle may be retracted from the tissue andbodily lumen and removed from the micropuncture guidewire. The near orproximal end of the micropuncture guidewire may be coupled to a far ordistal end portion of a guidewire extension such as with a male-femaleconnection, for example, a snap-fit, interference joint, or a threadedfit. The near or proximal end of the micropuncture guidewire and the faror distal end portion of guidewire extension may have the same diameter,such as 0.018″, while the far end of the guidewire extension may have agreater diameter, such as 0.035″. The coupled micropuncture guidewireand guidewire extension may be advanced through the tissue and bodilylumen such that a greater diameter near end portion and a taperingtransition portion of the guidewire extension are within the bodilylumen. The tapering transition portion may be disposed between thegreater diameter near end portion and the far end portion of theguidewire extension.

Aspects of the present disclosure also provide a sheath introducerapparatus which may be introduced over the micropuncture guidewire. Theinner diameter of the sheath may be of various sizes, for example 3, 4,5, or 6 Fr. The end of the inner dilator may be tapered to the samediameter as the micropuncture guidewire, such as 0.018″. The length ofthe sheath introducer apparatus may be long enough to insert a catheteror other over-the-wire device over the guidewire to access the bodilylumen or vessel. The inner diameter of the catheter or over-the-wiredevice may be greater than 0.018″, such as 0.035″.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the present disclosure are set forth withparticularity in the appended claims. A better understanding of thefeatures and advantages of the present disclosure will be obtained byreference to the following detailed description that sets forthillustrative embodiments, in which the principles of the presentdisclosure are utilized, and the accompanying drawings of which:

FIG. 1 shows a side view of the distal portion of a micropunctureguidewire, according to many embodiments;

FIG. 2 shows a side, section view of a current, standard typemicropuncture guidewire advanced into a blood vessel through anintroducer needle;

FIG. 3A shows a side, section view of the micropuncture guidewire ofFIG. 1 advanced into a blood vessel through an introducer needle,according to many embodiments;

FIG. 3B shows a side, section view of the micropuncture guidewire ofFIG. 1 and its flexible, neck segment forming into a loop as its distaltip encounters an obstruction in the blood vessel, according to manyembodiments;

FIG. 3C shows a side, section view of the micropuncture guidewire ofFIG. 1 and its flexible, neck segment advanced past the obstruction as aloop, pulling the distal tip distally past the obstruction, according tomany embodiments;

FIG. 4A shows a side section view of a current, standard typemicropuncture guidewire being introduced into a blood vessel through anintroducer needle;

FIG. 4B shows a side section view of the micropuncture guidewire of FIG.4A introduced into the blood vessel and the introducer needle withdrawn;

FIG. 4C shows a side section view of coaxial introducer dilators beingintroduced into the blood vessel over the micropuncture guidewire ofFIG. 4A;

FIG. 4D shows a side section view of the micropuncture guidewire of FIG.4A and the inner introducer dilator being withdrawn while the outerintroducer dilator remains;

FIG. 4E shows a side section view of a standard 0.035″ diameterguidewire being introduced into the blood vessel through the outerintroducer dilator of FIG. 4C;

FIG. 5A shows a side section view of the micropuncture guidewire of FIG.1 being introduced into a blood vessel through an introducer needle,according to many embodiments;

FIG. 5B shows a side section view of the micropuncture guidewire of FIG.1 being coupled to a guidewire extension after the introducer needle hasbeen withdrawn, according to many embodiments;

FIG. 5C shows a side section view the coupled micropuncture guidewireand guidewire extension of FIG. 5B being advanced further into the bloodvessel; according to many embodiments;

FIG. 5D shows a threaded fit between the micropuncture guidewire and theguidewire extension of FIG. 5B, according to many embodiments;

FIG. 5E show a snap fit between the micropuncture guidewire and theguidewire extension of FIG. 5B, according to many embodiments;

FIG. 5F shows another snap fit between the micropuncture guidewire andthe guidewire extension of FIG. 5B, according to many embodiments;

FIG. 5G shows an interference fit between the micropuncture guidewireand the guidewire extension of FIG. 5B, according to many embodiments;

FIG. 5H shows another interference fit between the micropunctureguidewire and the guidewire extension of FIG. 5B, according to manyembodiments;

FIG. 5I shows another interference fit between the micropunctureguidewire and the guidewire extension of FIG. 5B, according to manyembodiments;

FIG. 5J shows another interference fit between the micropunctureguidewire and the guidewire extension of FIG. 5B, according to manyembodiments;

FIG. 5K shows another interference fit between the micropunctureguidewire and the guidewire extension of FIG. 5B, according to manyembodiments;

FIG. 6 shows a side view of a micropuncture guidewire with multipletapered segments, according to many embodiments;

FIG. 7A shows a side section view of the micropuncture guidewire of FIG.1 being introduced into a blood vessel and the introducer needlewithdrawn;

FIG. 7B shows a side section view of an outer introducer sheath with aninner dilator being introduced into the blood vessel over themicropuncture guidewire of FIG. 1;

FIG. 7C shows a side section view of the micropuncture guidewire of FIG.1 and the inner dilator being withdrawn while the outer introducersheath remains; and

FIG. 7D shows a side section view of a catheter or other over-the-wiredevice being introduced into the blood vessel through the outerintroducer sheath and over the micropuncture guidewire of FIG. 1.

FIG. 8A shows a side view of a wire braid to support the flexible necksegment of a guidewire apparatus, according to many embodiments.

FIG. 8B shows the wire braid of FIG. 8A to be advanced over the flexibleneck portion.

FIG. 8C shows the wire braid of FIG. 8A advanced over the flexible neckportion and in a radially expanded, foreshortened configuration.

FIG. 8D shows the wire braid of FIG. 8A advanced over the flexible neckportion and in a radially collapsed configuration.

FIG. 9 shows a wire coil advanced over and supporting the flexible neckportion of a guidewire apparatus, according to many embodiments.

DETAILED DESCRIPTION

FIG. 1 shows a side view of the micropuncture guidewire 100, accordingto many embodiments. The micropuncture guidewire 100 may comprise anatraumatic distal tip 110. The atraumatic distal tip 110 may behemispheric or rounded and/or coated as described herein to minimizetrauma to tissue the tip 110 may encounter as the guidewire 100 isadvanced or retracted through a bodily lumen. As shown in FIG. 1, theatraumatic distal tip 110 may have a diameter of 0.018″. Alternatively,the atraumatic distal tip 110 may have the diameter of a standardguidewire, such as 0.035″.

The micropuncture guidewire 100 may further comprise a flexible segment120 proximal of the atraumatic distal tip 110. The flexible segment 120may be more flexible than the atraumatic distal tip 110. As shown inFIG. 1, the flexible segment 120 may comprise a distal tapering portion122, which tapers in the proximal direction. The flexible segment 120may further comprise a middle, flexible wire shaft portion 124, and aproximal tapering portion 126, which tapers in the distal direction. Thediameter of the guidewire 100 at the middle, flexible wire shaft portion124 may be 0.010″ or 0.0070″, for example. Alternatively, the diameterof the flexible segment 120 may be same as for the remainder of theguidewire 100. Alternatively or in combination, the flexibility of theflexible segment 120 may be provided by having the flexible segment 120being made of a different, more flexible material than the remainder ofthe guidewire 100, mechanically modifying the flexible segment 120 suchas with slots or cuts, and/or modifying the flexible segment 120 withcoating(s) in selected region(s) to increase stiffness in thoseregion(s). For example, the flexible segment 120 may be cut into theshape of a coil spring.

As shown in FIG. 1, the atraumatic distal tip 110 may be rounded andhave a greater diameter than the middle, flexible wire shaft portion 124and the atraumatic distal tip 110 tapers down to the lesser diameterover the distal tapering portion 122. Alternatively, the micropunctureguidewire 100 may omit the distal tapering portion 122 such that theatraumatic distal tip 110 has a rounded end and the same diameter as themiddle, flexible wire shaft portion.

The micropuncture guidewire 100 may further comprise an elongate wireshaft segment 130 proximal of the flexible segment 120. As shown in FIG.1, the elongate segment 130 may have a diameter of 0.018″.Alternatively, the elongate segment 130 may have the diameter of astandard guidewire, such as 0.035″. The elongate segment 130 may bestiffer than the flexible segment 120. Rather than having a sharptransition from the greater diameter atraumatic distal tip 110 and thegreater diameter elongate segment 130, the distal tapering portion 122and the proximal tapering portion 126 gradually transition to themiddle, flexible wire shaft portion 124. The distal tapering portion122, the middle, flexible wire shaft portion 124, and the proximaltapering portion 126 may combine to significantly reduce friction of theentire micropuncture guidewire 100 and provide better feedback, therebyreducing the risks of inadvertent perforation and dissection. Themiddle, flexible wire shaft portion 124 may have substantially the samediameter throughout. The combined length of the distal tapering portion122, the middle, flexible wire shaft portion 124, and the proximaltapering portion 126 may be 2-4 cm, for example.

FIG. 2 shows a side, section view of a current micropuncture guidewire210 advanced into a blood vessel 250 through an introducer needle 200.As the guidewire 210 is advanced through the blood vessel 250, theguidewire 210 may encounter obstructions in the blood vessel 250 such asplaque 260. To move the guidewire 210 past the plaque 260, the operatormay push the guidewire 210 with greater force. While attempting toadvance the guidewire 210 past the plaque 260, the guidewire 210 mayinstead perforate or otherwise damage the wall of the blood vessel 250in at least some cases. For instance, the guidewire 210 may encounterresistance from the inner lumen of the needle 200 and the operator maymistake the resistance from the plaque 260 as resistance from the needle200. Due to the poor tactile feedback, the operator may inadvertentlyapply too much force to the guidewire 210 and perforate or otherwisedamage the wall of the blood vessel 250.

FIG. 3A shows a side, section view of the micropuncture guidewire 100advanced into the blood vessel 250 through the introducer needle 200.The atraumatic distal tip 110 and the tapered segment 122 may beadvanced to encounter the plaque 260. In some embodiments, the smallerdiameter of the flexible segment 120 may reduce the degree of frictionencountered by the guidewire 100 as it is advanced through theintroducer needle 200. In FIG. 3B, the guidewire 100 is further advancedinto the blood vessel 250 such that the plaque 260 stops the advancementof the atraumatic distal tip 110 and the tapered segment 122 and theflexible segment 120 forms a loop distal of the atraumatic distal tip110. In FIG. 3C, the guidewire 100 is even further advanced so that thestiffer elongate segment 130 pushes the looped flexible segment 120beyond the plaque 260, pulling the distal tip 110 past the plaque 260 aswell. Once the distal tip 110 and the flexible segment 120 are advancedpast the plaque 260, the distal tip 110 and the flexible segment 120 mayresiliently straighten such that the distal tip 110 is distal of theflexible segment 120 once more.

FIGS. 4A to 4E show the standard method of advancing a micropunctureguidewire (e.g., 0.018″ in diameter) and replacing it with a standardguidewire (e.g., 0.035″ in diameter). FIG. 4A shows a standardmicropuncture guidewire 400 being introduced into the blood vessel 250through an introducer needle 200 penetrating tissue to access the bloodvessel 250. The standard micropuncture guidewire 400 may have a diameterof 0.018″ or the like throughout and one or more soldered segments atits tip and distal portion. In some embodiments, the atraumaticmicropuncture guidewire 100 may be used in lieu of the standardmicropuncture guidewire 400. The standard micropuncture guidewire 400may be advanced further into the blood vessel to cross areas ofextensive vascular disease such as plaques 260.

FIG. 4B shows the standard micropuncture guidewire 400 introduced intothe blood vessel 250 and the introducer needle 200 withdrawn. In someembodiments, the introducer needle 200 may be retracted over thestandard micropuncture guidewire 400 before the standard micropunctureguidewire 400 is further advanced. The introducer needle 200 may haveinner lumen with a diameter closely matching the outer diameter of thestandard micropuncture guidewire 400 and it may have soldered joints ator near its tip such that friction between the introducer needle 200 andthe standard micropuncture guidewire 400 may impede the advancement ofthe standard micropuncture guidewire 400.

FIG. 4C an inner introducer sheath 410 and a coaxial outer introducersheath 420 introduced into the blood vessel 250 over the standardmicropuncture guidewire 400. The inner introducer sheath 410 may have aninner lumen with a diameter closely matching the outer diameter of thestandard micropuncture guidewire 400. The inner introducer sheath 410may be advanced over the standard micropuncture guidewire 400 outsidethe body before being advanced through the tissue tract over thestandard micropuncture guidewire 400. The outer introducer sheath 420may have an inner lumen with a diameter closely matching the outerdiameter of the inner introducer sheath 410 and may be advancedthereover. The end of the outer introducer sheath 420 may be tapered tothe outer diameter of the inner introducer sheath 410 to facilitate itsadvancement into the tissue tract as the inner introducer sheath 410 isadvanced into the tissue.

FIG. 4D shows the outer introducer sheath 420 remaining in the tissuetract to access the blood vessel 250. After the coaxial introducersheaths 410, 420 are introduced into the blood vessel 250, the standardmicropuncture guidewire 400 and the inner introducer sheath 420 may bewithdrawn and removed so that a standard guidewire 430 may be advancedinto the blood vessel 250, replacing the standard micropunctureguidewire 400 as shown in FIG. 4E. The standard guidewire 430 may havean outer diameter less than or equal to the diameter of the inner lumenof the outer introducer sheath 420. For example, the standard guidewire430 may have a diameter of 0.035″. As shown in FIG. 4E, the standardguidewire can be advanced further into the blood vessel 250.

The withdrawal of the standard micropuncture guidewire 400 and the lateradvancement of the standard guidewire 430 can be disadvantageous in atleast some cases. There may be a greater likelihood of injury with theincreased number of steps of withdrawal and advancement. The largerstandard guidewire 430 may encounter difficulty or even failure incrossing one or more diseased vascular segments that the smallermicropuncture guidewire 400 had already successfully crossed through.

Aspects of the present disclosure also provide methods, systems, anddevices for advancing larger diameter guidewires where a micropunctureguidewire has already been introduced to address at least some of theaforementioned disadvantages.

FIG. 5A shows a micropuncture guidewire 500 of the present disclosurebeing introduced into the blood vessel 250 through the introducer needle200. The micropuncture guidewire 500 may have a uniform diameterthroughout or may have an atraumatic distal tip as described above andherein. For example, the micropuncture guidewire 500 may have a diameterof about 0.018″. As shown in FIG. 5A, the micropuncture guidewire 500may be advanced through areas of the blood vessel which may includediseased regions such as plaque 260. After the micropuncture guidewire500 is advanced, the introducer needle 200 may be withdrawn.

FIG. 5B shows the micropuncture guidewire 500 being coupled to aguidewire extension 510 with the introducer needle 200 having beenwithdrawn. The far end 500 f of the micropuncture guidewire 500 has beenadvanced past the plaque 260. The near end 500 n of the micropunctureguidewire 500 may couple to the far end portion 510 f of the guidewireextension 510. The coupling 505 may occur outside of the subject. Thediameters of the near end 500 n and the far end portion 510 f may be thesame, such as 0.018″. The guidewire extension 510 may comprise a far endportion 510 f, a tapering transition portion 510 t, and a near endportion 510 n which may have the diameter of a standard guidewire or0.035″. The micropuncture guidewire 500 and the guidewire extension 510may be constructed of the same materials or different materials.Examples of the materials include but are not limited to steel,stainless steel, copper, gold, silver, NiTi, to name a few. One or moreof the micropuncture guidewire 500 and the guidewire extension 510 maybe coated.

FIG. 5C shows the coupled micropuncture guidewire 500 and guidewireextension 510 being advanced further into the blood vessel 250. Theguidewire extension 510 may be advanced at least 10 cm into the bloodvessel 250, for example. The transition portion 510 t expands the tissuetract and blood vessel as it is advanced therethrough to minimize traumato the tissue when the larger diameter guidewire extension 510 isadvanced further into the blood vessel. An introducer sheath or otherover-the-wire device which may require the outer diameter of theguidewire extension 510 can then be advanced over the guidewireextension 510 to access the blood vessel 250. The introducer sheath maybe of various sizes such as 3, 4, or 5 Fr., for example. By coupling themicropuncture guidewire 500 and guidewire extension 510, a guidewire ofa standard size (i.e., 0.035″) can be introduced into blood vesselthrough an initial micropuncture (i.e., 0.018″ in diameter) accesswithout additional steps of withdrawing a smaller guidewire andre-advancing a larger guidewire using a succession of introducers 410and 420 as shown in FIGS. 4A-4E.

The far end portion 510 f of the guidewire extension 510 can be coupledto the near end 500 n of the guidewire 500 in many ways. In an exampleshown by FIG. 5D, the coupling 505 may comprise a threaded fit betweenthe threaded male connector of the far end portion 510 and the threadedfemale receptacle of the near end 500 n. In another example shown byFIG. 5E, the coupling 505 may comprise a snap fit between the maleconnector of the far end portion 510 and the female receptacle of thenear end 500 n. In an example shown by FIG. 5F, the coupling 505 maycomprise a snap fit of a different configuration between the maleconnector of the far end portion 510 and the female receptacle of thenear end 500 n. In an example shown by FIG. 5G, the coupling 505 maycomprise an interference fit between the male connector of the far endportion 510 and the female receptacle of the near end 500. In someembodiments, the male and female parts are reversed.

Also provided herein are further embodiments of interference fitsbetween the male connector of the far end portion 510 f and the femalereceptacle of the near end portion 500 n. In an example shown by FIG.5H, the coupling 505 may comprise an interference fit between the farend portion 510 f and the near end portion 500 n in which the far endportion 510 f of the male connector extends into the female receptacleof the near end 500. The far end portion 510 f of the male connector mayfurther comprise a tubular outer extension covering over the femalereceptacle of the near end 500 past the site of coupling 505. In anotherexample shown by FIG. 5I, the coupling 505 may comprise an interferencefit of a different configuration between far end portion 510 f and nearend portion 500 n. The male distal end 510 f of the far end portion 510may extend into the female receptacle and may also comprise an outerextension covering over the female receptacle of the near end portion500 n with a gradually tapering far end 510 f and a near end 500 n withpointed ends. FIGS. 5J and 5K show examples where the male and femaleparts are reversed so that the far end portion 510 receives the near endtip 500 n. In FIG. 5J, the coupling 505 may comprise an interference fitbetween the far end portion 510 f and the near end portion 500 n inwhich the ends of the far end portion 510 f extend and cover theguidewire 500 past the site of coupling. In FIG. 5K, the coupling 505may comprise an interference fit between the far end portion 510 f andthe near end portion 500 n in which the ends of far end portion 510 fextend and cover the guidewire 500 with a gradually tapering near end500 n and a far end 510 f with pointed ends.

The micropuncture guidewire 100 may further have multiple segments ofvarying diameters between the atraumatic tip 110 and the stiff wireshaft 130. As shown in FIG. 6, the flexible segment 120 may comprise adistal tapering portion 122, a middle flexible wire shaft portion 124 a,a proximal tapering portion 126 a, a second flexible wire shaft portion124 b, and a second proximal tapering portion 126 b. The diameter of theflexible wire shaft 124 a may be 0.002-0.004″ and the diameter of thewire shaft 124 b may be 0.004.″ Each section may be narrower in diameterthan the atraumatic tip 110 and the stiff wire shaft 130. The atraumatictip 110 of a guidewire with multiple segments may have a diameter of amicropuncture guidewire, such as 0.018″. Alternatively, the atraumatictip 110 of a guidewire with multiple segments may have the diameter of astandard guidewire, such as 0.035″. The stiff wire shaft 130 of aguidewire with multiple segments may have a diameter equal to orslightly smaller than that of the atraumatic tip 110. The micropunctureguidewire 100 with multiple segments may have a straight, curved(shaped) or shapeable proximal end and tip.

The stiff wire shaft 130 of a guidewire with multiple segments may havean end 130 e suitable for coupling with an extension guidewire. Thediameters of the stiff wire shaft 130 and the extension guidewire may bethe same. Alternatively, the diameter of the extension guidewire may beof a greater diameter than the stiff wire shaft 130 and comprise atapering transition portion and an end portion which may have thediameter of a standard guidewire or 0.035″.

The micropuncture guidewire with multiple segments may be a one piececonstruction from a single material or may be constructed from differentmaterials. In some embodiments, the micropuncture guidewire withmultiple segments may lack the hemispheric tip 110 and comprise aflexible wire shaft portion 124 a, a tapering portion 126 a, a secondflexible wire shaft portion 124 b, a second tapering portion 126 b, andthe stiff wire shaft 130 which may have a coupling site for an extensionguidewire.

The atraumatic guidewires described herein can eliminate many problemsassociated with conventional micropuncture guidewires. Because of thefriction resulting from a conventional micropuncture guidewire advancingthrough the lumen of an introducer needle, an operator may not be ableto differentiate whether resistance is due to friction of the guidewirewithin the needle or due to the guidewire tip meeting an obstruction inthe bodily lumen such as a plaque in a blood vessel or other obstructionto its path. The operator may use too much force, resulting in theinadvertent puncture or dissection of the bodily lumen such as a bloodvessel wall. By having tapered guidewire segments 126 a and 126 b and bylacking joints or welds between different guidewire components orsegments, there is decreased contact between the wire and lumen of theneedle, resulting in decreased friction and increased operator tactilefeedback. The softer hemispheric tip 110 and the soft and flexibletapered segments 122, 124 a, 126 a, 124 b, and 126 b, for example, canalso reduce complications resulting from the force exerted by theguidewire tip causing perforations, dissections, or other injuries tothe blood vessel or viscus.

Additionally, by having an end 130 e suitable for coupling an extensionguidewire of a larger diameter, the present disclosure reduces the risksand inconveniences from using two coaxial dilators to introduce a largerdiameter guidewire. With currently available micropuncture sets, when alarger diameter guidewire is needed, a coaxial double introducer dilatorset is used to introduce an inner 0.018″ diameter dilator and an outer0.035″ inner diameter dilator over the micropuncture wire. When theinner dilator and micropuncture guidewire are removed, the 0.035″dilator remains to allow the introduction of a larger 0.035″ guidewire,which must successfully re-cross the segment of the vessel or bodycavity previously crossed by the 0.018″ micropuncture guidewire. Thisattempted re-crossing may fail or may pose an injury threat. Theintroducer set and re-crossing can be rendered unnecessary by having anend 130 e on the micropuncture guidewire 100 that may couple to anextension guidewire, resulting in a one-step self-dilation of the entrysite. Another advantage of the micropuncture guidewire 100 with multiplesegments is that the single piece design, without joints, welds, orwrapping coils, can reduce complexity and cost of manufacturing.

FIG. 7A shows a micropuncture guidewire 500 initially introduced intothe blood vessel 250 through a micropuncture needle that has beenwithdrawn. The micropuncture guidewire 500 may have a diameter of 0.018″and may have a length of 180 cm or, alternatively, a length greater than180 cm. The micropuncture guidewire 500 may be substantially advancedthrough the micropuncture needle so that a short length, such as 20 cm,remains outside of the body.

As shown in FIG. 7B, an outer introducer sheath 700, with an innerdilator 710, may be advanced over the micropuncture guidewire 500. Theouter introducer sheath 700 may have an inner diameter of various sizessuch as 3, 4, or 5 Fr, or may be of a size greater than 5 Fr. The innerdilator 710 may have an outer diameter of various sizes such as 3, 4, or5 Fr, or may be of a size greater than 5 Fr. The inner dilator 710 mayhave a tip 710 t that is tapered, for example, to 0.018″. The outerintroducer sheath 700 and inner dilator 710 may have a length that islong enough to reach a site of pathology. Alternatively, the outerintroducer sheath 700 and inner dilator 710 may have a short length,such as 10 cm, to remain in the iliac artery. The outer introducersheath 700 may have a sidearm 720 with a stopcock.

FIG. 7C shows the outer introducer sheath 700 remaining in the bloodvessel 250 after the inner dilator 710 has been removed. In FIG. 7D, acatheter or other over-the-wire device 730 may be introduced over themicropuncture guidewire 500 through the outer introducer sheath 700 andadvanced into the blood vessel 250. The catheter or other over-the-wiredevice 730 may have an outer diameter less than or equal to the diameterof the inner lumen of the outer introducer sheath 700. The catheter orother over-the wire device 730 may have an inner diameter equal to orgreater than 0.018″. After introduction of the catheter or otherover-the-wire device 730 into the blood vessel 250, the micropunctureguidewire 500 may be withdrawn and removed so that other guidewires maybe advanced into the blood vessel 250, such as guidewires with an outerdiameter equal to the inner diameter of the catheter or otherover-the-wire device 730.

Further features may be provided to support the flexible neck segment ofthe guidewire apparatuses described herein, for example, as theguidewire apparatus is withdrawn into an introducer sheath or punctureneedle. For example, a wire coil or braid may extend from the beginningof the “comet” taper 122 to the end of the second transition or taper126 (referring to FIG. 1). Referring to FIG. 9, the support feature maycomprise a wire coil 900 wound on the wire shaft (e.g., wire shaft 124)and can be attached on one or more of its proximal or distal ends to the(e.g., distal taper 122 and/or proximal taper 126) such as with glue,solder, or the like. Alternatively or in combination, the wire coil maybe made of a material with shape memory characteristics (such asNitinol) and can be configured to be shaped as a straight wire at verylow temperatures but resumes a coil configuration after being applied tothe wire shaft (e.g., wire shaft 124) at normal operating temperatures(e.g., body temperature). Alternatively or in combination, the supportfeature may comprise a wire coil or braid 800 (referring to FIGS.8A-8D), which may be similar to many braided stent configurations. Whenpushed from its ends to shorten, the wire braid may increase in diameterso it can be slipped over the tip of the guidewire apparatus (e.g., tip110) and subsequently pulled to its full length before attachment to theguidewire apparatus (e.g., at distal taper 122 and/or proximal taper126) such as by glue, solder, or the like. Alternatively or incombination, the wire shaft may simply be cut or shaped to provideimproved support when withdrawn. Such support features are furtherdiscussed as follows.

The thin tip segment between the proximal end of the comet tip (i.e.,hemisphere 110 and decreasing taper 122) of the guidewire apparatus 100and the expanding taper 126 to the full shaft diameter proximally is theoften most vulnerable to being sheared off or being deformed duringinvasive procedures especially during introduction and withdrawal of thewire 100 through puncture needles or catheter based devices. Protectingor reinforcing this portion of the wire (i.e., the flexible segment 120)may be necessary. It may also be very important to retain the uniquedesign characteristics of the guidewire tip: softness and flexibility,while reinforcing it. A thin wire braid 800 and/or a spiral coil 900 mayadd significant protection and reinforcement but very little extrastiffness and rigidity to the guidewire. The contours and narrowerdiameter of the thin segment 120 of the guidewire 100 over which thereinforcement is applied will typically not be augmented to the maximumdiameter of the rest of the guidewire. Below are examples by which thesedesign goals may be achieved:

Braid:

Referring to FIG. 8A, a wire braided “tube” 800 of suitable length anddiameter is compressed to shorten it (e.g., along the axial/longitudinaldirections indicated by arrows 801) and increase its diameter to begreater than that of the comet tip 110 or guidewire shaft flexiblesegment 120.

Referring to FIG. 8B, the compressed braid 800 can be slipped over theguidewire apparatus 100 such as indicated by the arrow 802.

Referring to FIG. 8C, the braid 800 can be stretched over the thinnestsegment 120 of the guidewire apparatus 100 (e.g., along theaxial/longitudinal directions indicated by arrows 803) and over theincreasing diameter tapers 122, 126 at both its ends.

Referring to FIG. 8D, both ends of the braid 800 can be bonded to theincreasing diameter tapers 122, 126 of the guidewire apparatus 100.

Spiral Coil:

There are at least three ways to apply a spiral wire coil 900 to thethinnest segment 120 of the guidewire apparatus 100 and to the expandingtapers 122, 126 at both its ends:

(A) Using Shape Memory Nitinol wire which changes shape at differenttemperatures:

The spiral wire coil 900 may comprise a shape memory metal (e.g.,Nitinol) wire that may be shaped into a spiral coil configuration ofsuitable length and diameter and which can maintain that shape at bodytemperature. When chilled, the coil 900 can be manipulated andstraightened for the assembly process.

The cold nitinol wire can then be suitably positioned with relation tothe desired segment 120 of the guidewire apparatus 100.

The temperature of the coil 900 can be increased, allowing the coil 900to remember it's shape. The coil 900 can be allowed to form into aspiral coil around the desired segment 120 of the guidewire apparatus100.

Both ends of the spiral coil 900 are bonded to the increasing diametertapers 122, 126 of the guidewire apparatus 100.

(B) Using a length of wire coil (similarly to the technique describedabove for the braid 800):

A wire coil “cylinder” 900 of suitable length and diameter can be formedwith the turns maximally compressed.

The coil 900 can be slipped over the guidewire (as in FIGS. 8B and 8C,for example).

The coil 900 can be stretched and its two ends can be pulled over thethinnest segment 120 of the guidewire apparatus 100 and over theincreasing diameter tapers 122, 126 at both its ends.

Both ends of the braid 900 can be bonded to the increasing diametertapers 122, 126 of the guidewire apparatus 100.

(C) Using standard techniques of a winding spiral coil on a mandril:

Both ends of the guidewire apparatus 100 can be fixed and the coil 900can be wound circumferentially over the desired portion of the guidewireapparatus 100 (e.g., the thin segment 120).

Both ends of the spiral coil 900 can be bonded to the increasingdiameter tapers 122, 126 of the guidewire apparatus 100.

While preferred embodiments of the present disclosure have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the present disclosure. It should beunderstood that various alternatives to the embodiments of the presentdisclosure described herein may be employed in practicing the presentdisclosure. It is intended that the following claims define the scope ofthe invention and that methods and structures within the scope of theseclaims and their equivalents be covered thereby.

What is claimed is:
 1. A guidewire apparatus advancable through a bodilylumen, the guidewire apparatus comprising: a hemispheric distal tiphaving an equator with a first diameter; a flexible neck segmentproximal of the hemispheric distal tip and having a second diameter lessthan the first diameter of the hemispheric distal tip, the flexible necksegment having: (i) a middle portion having the second diameter, (ii) adistal tapering portion where the equator of the hemispheric distal tiptapers proximally to transition into the middle portion, and (iii) aproximal tapering portion proximal the middle portion; an elongatesegment proximal of the proximal tapering portion of the flexible necksegment and having a third diameter greater than the second diameter ofthe flexible neck segment; and a wire-braided tube disposed over andsupporting the flexible, neck segment, wherein the wire-braided tubecomprises a distal tapering region and a proximal tapering region, thedistal tapering region being configured to align with the distaltapering portion of the flexible neck segment, and the proximal taperingregion being configured to align with the proximal tapering portion ofthe flexible neck segment, wherein the flexible neck segment isconfigured to form into a loop as the guidewire apparatus is advancedthrough the bodily lumen and the hemispheric distal tip encounters anobstruction, the loop being distal of the hemispheric distal tip withinthe bodily lumen, and wherein further advancement of the guidewirepushes the loop past the obstruction so that the hemispheric distal tipis pulled by the flexible neck segment past the obstruction.
 2. Theguidewire apparatus of claim 1, wherein one or more of the hemisphericdistal tip, the flexible neck segment, or the elongate segment iscovered with a coating.
 3. The guidewire apparatus of claim 2, whereinthe coating comprises a hydrophobic coating, a hydrophillic coating, ananti-thrombogenic coating, a polymeric coating, a silicone coating, or apolytetrafluoroethylene (PTFE) coating.
 4. The guidewire apparatus ofclaim 1, wherein the guidewire apparatus is made of a materialcomprising one or more of platinum, gold, silver, NiTi, steel, steelalloy, stainless steel, stainless steel alloy, titanium, titanium alloy,aluminum, aluminum alloy, tungsten, or tungsten alloy.
 5. The guidewireapparatus of claim 1, wherein the first diameter is about 0.018 inches.6. The guidewire apparatus of claim 1, wherein the second diameter isabout 0.010 inches.
 7. The guidewire apparatus of claim 1, wherein thethird diameter is about 0.018 inches.
 8. The guidewire apparatus ofclaim 1, wherein the bodily lumen comprises a bodily duct, a bodilytrack, a bodily orifice, a bodily invagination, a blood vessel, anartery, a vein, a urethra, a ureter, a vagina, a fallopian tube, arectum, a throat, an ear canal, a nasal tract, a bile duct, a biliarytract, an esophagus, a trachea, a bronchus, or an artificial bodilytract or lumen.
 9. The guidewire apparatus of claim 1, wherein theobstruction comprises plaque in a blood vessel.
 10. The guidewireapparatus of claim 1, wherein the hemispheric distal tip is biased toreturn to a position distal of the flexible neck segment within thebodily lumen after the loop of the flexible neck segment is advancedpast the obstruction and the hemispheric distal tip is pulled past theobstruction.
 11. The guidewire apparatus of claim 1, wherein theflexible neck segment is biased so that the loop straightens after theloop of the flexible neck segment is advanced past the obstruction andthe hemispheric distal tip is pulled past the obstruction.
 12. Theguidewire apparatus of claim 1, wherein the wire-braided tube isremovably attached to the flexible neck segment.
 13. The guidewireapparatus of claim 1, wherein the wire-braided tube is disposed over andbonded to one or more of the distal tapering portion or the proximaltapering portion of the flexible neck segment.
 14. The guidewireapparatus of claim 1, wherein a combined diameter of the wire-braidedtube and the flexible neck segment is less than each of the firstdiameter of the hemispheric distal tip and the third diameter of theelongate segment.
 15. The guidewire apparatus of claim 1, wherein thesecond diameter of the flexible, neck segment is less than the firstdiameter such that the flexible, neck segment is more flexible than thehemispheric distal tip.
 16. The guidewire apparatus of claim 1, whereinthe third diameter of the elongate segment proximal of the neck segmentis greater than the second diameter of the flexible, neck segment suchthat the flexible, neck segment is more flexible than the elongatesegment proximal thereto.
 17. A guidewire apparatus advancable through abodily lumen, the guidewire apparatus comprising: an atraumatic distaltip having a first diameter; a flexible segment proximal of theatraumatic distal tip and having a second diameter less than the firstdiameter, the flexible segment comprising a middle portion having thethird diameter and tapering proximal and distal portions havingdiameters greater than the third diameter; an elongate segment proximalof the flexible segment and having a third diameter greater than thesecond diameter; a wire-braided tube disposed over and supporting theflexible segment, wherein the wire-braided tube comprises a middleregion, a distal tapering region, and a proximal tapering regionconfigured to align with and be disposed over the middle portion, thedistal tapering portion, and the proximal tapering portion,respectively, of the flexible segment, the distal and proximal taperingregions of the wire-braided tube having diameters greater than adiameter of the middle region, wherein the flexible segment isconfigured to form into a loop as the guidewire apparatus is advancedthrough the bodily lumen and the atraumatic distal tip encounters anobstruction, the loop being distal of the atraumatic distal tip, andwherein further advancement of the guidewire pushes the loop past theobstruction so that the atraumatic distal tip is passed through theobstruction.
 18. The guidewire apparatus of claim 17, wherein one ormore of the atraumatic distal tip, the flexible segment, or the elongatesegment is covered with a coating.
 19. The guidewire apparatus of claim17, wherein one or more of the atraumatic distal tip or the elongatesegment comprises a first material, and wherein the flexible segmentcomprises a second material different from and more flexible than thefirst material.
 20. The guidewire apparatus of claim 17, wherein one ormore of the atraumatic distal tip or the elongate segment comprises afirst material, wherein the flexible segment comprises further comprisesthe first material, and wherein the flexible segment is mechanicallymodified to be more flexible than one or more of the atraumatic distaltip or the elongate segment.
 21. The guidewire apparatus of claim 20,wherein the flexible segment has one or more slots or cuts to provideflexibility.
 22. The guidewire apparatus of claim 17, wherein theatraumatic distal tip is biased to return to a position distal of theflexible segment after the loop of the flexible segment is advanced pastthe obstruction and the atraumatic distal tip is pulled past theobstruction.
 23. The guidewire apparatus of claim 17, wherein theflexible segment is biased so that the loop straightens after the loopof the flexible segment is advanced past the obstruction and theatraumatic tip is pulled past the obstruction.
 24. The guidewireapparatus of claim 17, wherein the bodily lumen comprises a blood vesseland the obstruction comprises plaque in the blood vessel.
 25. Theguidewire apparatus of claim 17, wherein the wire-braided tube isremovably attached to the flexible segment.
 26. The guidewire apparatusof claim 17, wherein the wire-braided tube is disposed over and bondedto one or more of a distal transition region between the atraumaticdistal tip and the flexible segment or a proximal transition theflexible segment.
 27. The guidewire apparatus of claim 17, wherein acombined diameter of the wire-braided tube and the flexible segment isless than a diameter of the atraumatic distal tip and a diameter of theelongate segment.